Impact of Surface Roughness on Corona Discharge for 30-year Operating Conductors in 500-kV ac Power Transmission Line

An investigation into the effect of surface roughness on corona discharge for a 30-year operating conductor in the first 500-kV transmission line in China is presented. Many substances were found to adhere to the conductor surface. Corrosion and deposits had rendered the operated conductor surfaces much rougher than those of the new one. The results show that surface roughness has a significant impact on corona discharge, and the corona inception voltage of the operated conductor would be reduced while the audible and radio noise would be increased.